This invention relates to fluidic devices, in particular to devices in which fluid flow can be controlled by producing a vortex in the fluid so as to present a higher resistance to flow in one direction than in the other. Such devices are termed vortex diodes.
A known form of vortex diode comprises a thin cylindrical chamber having a tangential port in the peripheral wall thereof and an axial port in an end wall thereof, the fluid entering and leaving the device through these ports. There are two modes of operation. If the fluid flow enters through the axial port and exits through the tangential port no appreciable vortex is formed and the resistance to flow is relatively small. However, if the flow enters through the tangential port and exits through the axial port a vortex is formed within the chamber and the resistance to flow is relatively high. These two modes of operation are herein termed low and high resistance modes respectively.